PROJECT SUMMARY The overall goal of our proposed work is to study the underlying pathomechanisms of a repeat expansion found in C9ORF72 that causes frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Indeed, various studies have shown that C9ORF72 is bidirectionally transcribed and the RNA repeat expansions have toxic gain-of-functions. Our studies will comprehensively characterize the RNA gain-of- function, defining therapeutic targets and pathways. These studies will be enabled by the development of small molecule chemical probes that inhibit RNA toxicity. Core B will support the efforts of all three projects to speed therapies and biomarkers to c9FTD/ALS patients. Core B consists of three components: medicinal chemistry, drug metabolism and pharmacokinetics, and three cores (Genomics/Next Generation Sequencing, Proteomics, and Imaging). Core B will be spearheaded by The Scripps Research Institute's Translational Research Institute (TRI). TRI combines basic research with advanced technology platforms to develop potential lead compounds that can prevent, treat or cure disease. TRI works closely with the Scripps Florida academic departments to bring translational approaches to bear on complex biological problems and is comprised of Discovery Biology, Drug Metabolism and Pharmacokinetics (DMPK), TRI-Informatics, Lead Identification and HTS, and Medicinal Chemistry. The Specific Aims are: Aim 1: Hit-to-lead optimization: synthesis of compound derivatives. Core B will be responsible for the design and synthesis of second/third generation compounds based on studies completed in Project 1 (in vitro potency, cellular selectivity, inhibition of foci formation and RAN translation in cellular models) and Project 2 (activity in patient-derived lymphoblastoid cells). Aim 2: Evaluation of compounds as in vivo chemical probes: Drug Metabolism and Pharmacokinetics (DMPK). While potency and selectivity against the target are vitally important, optimization of compounds for in vivo applications (as in Project 2) requires a detailed understanding of the molecule and its liabilities. Thus, Aim 2 will fully characterize DMPK profiles for lead optimized compounds from Aim 1 to identify the most suitable in vivo chemical probes and to guide further refinement of lead compounds. Aim 3: Proteomics, Next Generation Sequencing, and Imaging. The remaining three components of Core B are Next Generation Sequencing (Genomics), Proteomics, and Imaging Cores, which will support studies proposed in all three project, ranging from exploring RNA metabolism and splicing caused by the c9FTD/ALS repeat expansion to identification of protein components of foci to studying nuclear pore and transport abnormalities.